Old Fashioned Peanut Butter Sheet Cake
Peanut butter lovers will rave about this classic dessert! Moist and dense peanut butter sheet cake covered with rich peanut butter fudge frosting, it’s Peanut Butter Paradise! Old Fashioned Peanut Butter Sheet Cake has been around a long time and for good reason. It’s quick and easy to make, uses simple ingredients, and tastes like grandma made it! It’s quite different from most cake recipes though, so keep reading!
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I remember having this cake as a kid growing up at various church functions and pot lucks. It’s similar to peanut butter bars or brownies, but more cake like than brownie like. The buttermilk in the recipe helps give it the rich flavor that makes this cake stand out. If you don’t want to buy buttermilk, it’s easy to substitute by adding 1 tablespoon of vinegar to a cup of milk. Here are some other great ways to substitute for buttermilk in your recipes.
What makes this cake recipe different from most?
1. Boiling the liquid ingredients.
This sheet cake recipe starts out like most cake recipes: combine the dry ingredients separately. But the next step is an odd one. For many cake recipes you cream together the butter and sugar. For Peanut Butter Sheet Cake, however, you combine the peanut butter, water, and butter in a saucepan and bring it to a boil. Then you add the eggs and buttermilk before stirring it into the flour mixture.
2. Boiling the frosting ingredients.
While the cake is baking, you prepare the frosting by boiling the butter, peanut butter, and buttermilk together. Then you add the vanilla and powdered sugar. This boiling step is what helps give the frosting it’s fudge-like texture. Also, like fudge, it forms a crust which makes it so much easier to transport and serve the sheet cake.
3. Frosting the cake while hot.
For most cake recipes, you cool the cake completely before adding the frosting. Otherwise the frosting will melt and you have a giant mess on your hands. Sadly I know this from experience. But with this cake, you’ll want to pour over and spread the frosting while the cake is hot from the oven. This helps the frosting to spread easier, and also helps keep the cake itself moist and dense. You do want to be quick about it though, or the frosting sets up too quickly and will be hard to spread smoothly. In my pictures you can see the frosting didn’t spread as easily as it should. This is because I was trying to take pictures for this post and took too long frosting it.
The fact that the peanut butter fudge frosting sets up and forms a crust is what makes it perfect for transporting to potlucks or parties. It’s easy to wrap and cover, and slicing and serving it is a breeze. You can serve it with plates and forks if you wish. But since it’s more like a snack cake, or like brownies, you can serve it on napkins to be eaten with hands.
The recipe states that it serves 24, but you can get more servings out of it by cutting smaller slices. This cake is so rich and sweet that smaller slices are probably a good idea. Regardless, folks will come back for just one more slice!
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Old Fashioned Peanut Butter Sheet Cake
Ingredients
Peanut Butter Sheet Cake
- 2 cups all purpose flour 256g
- 2 cups sugar 400g
- 1 tsp salt
- 1 tsp baking soda
- 1 cup peanut butter 240g
- 1 cup butter 227g, 2 sticks
- 1 cup water 237ml
- 1/2 cup buttermilk 118ml
- 2 eggs
Peanut Butter Frosting
- 1/2 cup peanut butter 120g
- 1/2 cup butter 113g, 1 stick
- 6 tbsp buttermilk
- 1 tsp vanilla
- 4 cups powdered sugar 500g
Instructions
- Preheat oven to 350F (180C). Grease a sheet pan (also called half-sheet pan and measures 13×18 inches and about an inch deep).
- Combine flour, sugar, salt, and baking soda in medium bowl. Set aside.
- In a saucepan, bring peanut butter, water, and butter to a boil. Remove from heat and add the buttermilk and eggs. Pour over flour mixture and combine until smooth.
- Pour the cake batter into the sheet pan and spread evenly. Bake at 350F (180C) for 20-25 minutes, or until toothpick comes out clean. Do not over bake. (Mine is typically done at 20 minutes.)
Prepare Peanut Butter Frosting
- While cake is baking, add the powdered sugar to a medium bowl. Combine the peanut butter and butter in a saucepan and melt. Add buttermilk and bring to a boil. Remove from heat and add vanilla. Pour over powdered sugar and combine. Stir until no lumps remain.
- When cake is finished baking, immediately spread peanut butter frosting over the cake. Be careful not to tear the cake while spreading it. Work quickly as the frosting will set up as it cools, making it harder to spread.
- Cool completely and cut into squares to serve.